This invention relates to multi-chip liquid cooled integrated circuit modules. Two U.S. Pats. which are representative of the prior art on these modules are 4,138,692 to Meeker et al and 4,561,040 to Eastman et al.
In both of the above patents, a substrate is provided on which several integrated circuit chips are mounted, and patterned conductors in the substrate electrically interconnect the chips. Also, a liquid cooling apparatus is provided which transfers heat from the chips. However, the present inventors have analyzed this cooling apparatus and have discovered that it ha certain deficiencies.
In particular, in both of the patents '692 and '040, separate hollow bellows-shaped tubes carry a liquid coolant to and from each of the chips. Each of these bellows-shaped tubes has one end which is attached to a solid thermally conductive end plate which makes contact with a chip, and it has an opposite end that attaches to a manifold which is the source of the liquid coolant.
However, due to the presence of these bellows-shaped tubes, the above cooling apparatus has a large number of seams. Two seams occur at each bellows. And, if just one of those seams develops a leak, it will cause the chips to malfunction.
In FIG. 2 of Pat. '692, each of the bellows is indicated by reference numeral 21. One end of each bellows 21 is joined to a stud 22B, while the opposite end of each bellows 21 is joined to a plate 16B which is part of a manifold that supplies the liquid coolant. If the seam at either end of any one of these bellows 21 has a leak, then all of the chips 10 in the entire module will be submerged in the liquid coolant.
Such submersion will short the terminals of all of the chips together if the coolant is electrically conductive. In that case, the malfunction would be quick and catastrophic. Further, even if the liquid coolant is non-conductive, it will expose the chips to various contaminants. These contaminants would be washed to the chips from anywhere in the entire cooling system, such as from solder material at the leaky joint, and they would cause long term reliability problems.
These same problems occur in the cooling apparatus of Pat. '040. See, for example, FIG. 1 in which the bellows-shaped tubes are indicated by reference numeral 32. Reference numeral 32A indicates a flange on one end of the bellows 32 which makes a seam with a cooling plate 24. Each bellows 32 also makes a seam at its opposite end as can be seen from FIG. 4.
Making these seams leakproof is a tedious and costly task which is not well suited for a mass production environment. Further, these manufacturing problems become worse as the number of bellows per module increases, and as the size of the bellows decreases.
Accordingly, a primary object of the invention is to provide a multi-chip liquid cooling module in which all of the above problems are overcome.